Electric cars and other electric-motor driven vehicles are known in the art, including so-called hybrid vehicles which use one or another combination of electric motor and fossil-fuel powered motor, which is in some cases a gas turbine, such as disclosed in U.S. Pat. No. 3,477,537, for an ELECTRIC MOTOR-DRIVEN AUTOMOBILE, issued Nov. 11, 1969, to the inventor of the present invention. The gas turbine of the '537 patent drives an electric generator, which in turn drives one or more electric motors, or charges an electric power source device—a fuel cell or battery—or does both, sometimes doing one under some driving conditions and doing the other under other driving conditions.
Besides hybrid vehicles using turbine engines as one power source, major automobile manufacturers, including Honda and Toyota, are now developing gasoline-electric hybrid vehicles. In these cars, a transmission is turned by, under some conditions, both a gasoline engine and an electric motor, and the transmission then turns the wheels of the vehicle in the same way as is done conventionally. (Thus, for such hybrid vehicles, there is only one electric motor providing a driving force/torque for all of the drive wheels, of which there are always at least two.)
In case of a pure electric vehicle, instead of a motor driving a generator, a fuel cell is often used as a source of electric power.
In case of an electric vehicle or a so-called series hybrid vehicle, as in the '537 patent, the drive force is provided (through more or less of a transmission system) by one or more electric motors, as opposed to other arrangements including a so-called parallel hybrid arrangement in which both a fossil-fueled motor and an electric motor cooperate to provide a drive force via a transmission.
Now in case of at least a series hybrid vehicle—even one having more than one electric motor—it would be advantageous to be able to quickly recover from failure of the electric power source, which would allow continued normal operation of the vehicle. The need for this is especially acute in military operations in battlefield conditions, where a power source failure can mean the crew is likely to be surrounded and possibly killed by enemy troops before help can arrive. Also, in case of an electric vehicle, a fuel cell can sometimes take so long to recharge that it is advantageous to have another source of electric power on the ready, which would again allow normal operation of the vehicle.
Thus, what is needed is a way to continue to provide electric power for an electric or hybrid vehicle when there is a failure of the main electric power source, i.e. in case of an electric vehicle, a state of discharge of the fuel cell, and in case of a hybrid including a motor-generator combination providing electric power to an electric motor, a failure of the electric generator that would ordinarily provide electric power for the electric motor, or a failure of the motor driving the electric generator.